Midland Syn-Tech 70-342XL Service Manual page 50

CPU/PLL TROUBLESHOOTING CHART
7 0 - 3 4 2 ~ ~ / 4 4 2 ~ ~
R e c e i v e r o f f
D i s p l a y e d
E r r o r
Code
94
i s D i s p l a v c d and 9 3 a r e d i s p l a y e d
S u b s t i t u t e
EIPROM
S u b s t i t u t e E/PROM
Check for 2.5MHz
Module
at
IC702 P i n 12
-
OK
p i n s 1, 6
&
7 bv s w i t c h i n g
+
Check f o r p u l s e s o n IC701
None Check f o r p u l s e s a t IC901
N o Pulses
Check f o r p u l s e s i n p u t on 1 ~ 9 0 1
T.7~2 o n TP701 Q703, 5 . 1 2 MHz
p i n s 1 , 4 0 , 4 1 , 4 2 by s w i t c h -
.
p i n s 1 . 4 , 5 , 6 , 7 , 1 3 , 1 4
&
1 5 by
Check C M l O l
f r o m Rx t o Tx t o Rx i n g from RX t o T X t o R X a t p i n 4 1 s w i t c h i n g from RX t o T X t o R X
OK No P u l s e s a t P i n s A l l a r e
?, 4 0 o r 42 H i o r Lo
\I
Dl07 a n o d e h i g h
r
1
Turn r a d i o o f f and momen- S u b s t i t u t e ElPROM
t a r i l y g r o u n d p i n 2 1 o f
-
Module
I C 9 0 1 , t h e n t u r n thd r a d i o o
A l l
a r e
I
A l l a r e s t i l l
-
Problem i s
HI o r Lo
T
H i o r 1.0
Check f o r Loc. Osc.
No T r a n s m i t ,
Check f o r p u l s e s on IC901
-
1
Check f o r P u l s e s on IC
[ c h e c k f o r +5VDC on p i n 1 9 , 2 0
1
-
p i n s 3 2 . 3 3 , 3 4 , 3 5 , 3 6 , 3 7
&
)
701 p i n s 4
&
5
and 2 1 o f IC 9 0 1 , OV on p i n 1 5
3 8 by s w i t c h i n g from RX
t o T X t o RX
OK
Check f o r RF a t V C O
11
o s c i l l a t o r Q707, Check 8 0 0 KHz c l o c k I f r a d i o h a s BCLO c h e c k s q u e l c h ;
(RX LO) a t 5 3 6 5
IC704 B u f f e r 4708
on IC901 p i n s 1 7 & 1 8
t h e n c h e c k i f p i n 2 8 o f IC901 i s Lo.
A
t
OK
I
O K
Check t h e D C Amp. 4 7 0 4 ,
S h o o t i n g C h a r t Check i f p i n 30 o f IC901 g o e s
0 7 0 5 , 4706 I C 7 0 1 , p i n 11
Check IC401 & 1 ~ 4 0 2 OK
H i i n T r a n s m i t Mode
Lo T r a n s m i t o r R e c e i v e
-
V o l t a g e R e g u l a t o r s
Recheck IC901 i n p u t c o n t r o l p i n s
N~~~ Check f o r p u l s e s on IC901
P i n 4 Lo R e c e i v e r i n S t a n d b y ?lode
p i n s 1 0 , 1 1 , 2 2 , 2 3 , 2 3 & 25 P i n 6 H i Main VCO u n l o c k from IC701 p i n 1 0 c c e i v e O K b u t c a n n o t t r a n s m i t ,
by c h a n g i n g c h a n n e l s P i n 8 H i Scan B u t t o n Out ed tranqmi
f
I.FD n o t on
P i n 9 H i P r i m a r y B u t t o n Out
OK
P l n 26 H i C h a n n e l S w i t c h i n n e u t r a l p o s i t i o n
Check f o r p u l s e on IC301 and
None
r l
P i n 27 H i C h a n n e l S w i t c h i n n e u t r a l p o s i t i o n
Same
Check IC402 IC302 on p i n s 1 , 2 , 5 , 6 & 7 P i n 2 8 Lo R e c e i v e r i n S t a n d b y Mode
by c h a n g i n g c h a n n e l s P i n 29 H i R e c e i v e r i n S t a n d b y Mode
1
P i n 30 Lo R e c e i v e r i n S t a n d b y Mode
I I
P i n 3 1 Lo R e c e i v e r i n S t a n d b y Mode
C o n f i r m t h a t IC901 p i n 26
OK
C o n f i r m t h a t I C 9 0 1 p i n 8 g o e s low S u b s t i t u t e ElPROM
g o e s low i n DN C h a n n e l a n d
4
i n SCAN mode and p i n 9 g o e s low Module
p i n 27 g o e s .low i n Up C h a n n e l
i n PRI mode. Sq. S i g i s Lo a t p i n 4.
1
I
Check IC303 +BVDC
S U P P ~ V
1
I 1
I
1
R e c e i v e Mode
1 I
T r a n s m i t ~ o d e l
1
T r a n s m i t & R e c e i v e O K ~
1
S u b s t i t u t e ElPROM T r a n s m i t and R e c e i v e O K
Module Cannot c h a n g e c h a n n e l
Check R e c e i v e r
D i s p l a y i s B l a n k o r
1
Q7~;;cBasc i s
I 1
Q40;v;fse
i s
1 1
i n c o r r e c t
1
I
T r a n s m i t and R e c e i v e
OK, No S c a n
I
Fold Out
-